Antibodies represent a class of therapeutic molecules with applications in many different areas including transplantation, cardiovascular diseases, infectious diseases, cancer, and autoimmunity. The development of hybridoma technology has enabled the isolation of monoclonal antibodies (also referred to as MAbs) as candidate therapeutic molecules. MAbs now constitute a rapidly growing class of therapeutic, due in part to their predictable pharmacokinetic properties, their high success rate in the clinic, and their ability to antagonize large protein-protein interactions.
Chemoattractant receptors represent a class of G-protein coupled receptors that facilitate cell migration (Gerard, et al., Ann. Rev. Immunol. 12:775-808 (1994a); Gerard, et al., Curr. Opin. Immunol. 6:140-145 (1994b); Murphy, Ann. Rev. Immunol. 12:593-633 (1994)). These receptors have attracted the interest of numerous pharmaceutical companies, since they are usually amenable to inhibition by organic small molecules, and blocking these receptors or their ligands ameliorates various inflammatory conditions, at least in animal models (Mackay, Nat. Immunol. 2:95-101 (2001); von Andrian, et al., N. Engl. J. Med. 343:1020-1034 (2000); and Luster, et al., Nat. Immunol. 6:1182-1190 (2005)). One receptor that plays a critical role in numerous inflammatory conditions is the receptor for C5a (C5aR) (Gerard, et al., Curr. Opin. Immunol. 6:140-145 (1994b); Guo, et al., Ann. Rev. Immunol. 23:821-852 (2005); Riedemann, et al., J. Clin. Invest. 112:460-467 (2003); Ji, H., et al., Immunity 16:157-168 (2002)). Considerable effort has gone to developing human C5aR antagonists, including organic small molecules and peptide antagonists (Sumichika, Curr. Opin. Investig. Drugs 5:505-510 (2004); Allegretti, et al., Curr. Med. Chem. 12:217-236 (2005)). Despite this effort, the development of suitable small molecule antagonists for C5aR and other chemoattractant receptors has proven problematic.
Recently, monoclonal antibodies (mAbs) have proven to be useful agents to antagonize chemoattractant receptors, and to identify important regions for chemokine/ligand binding, or HIV-I binding (Heath, et al., J. Clin. Invest. 99:178-184 (1997)). However, the generation of high affinity antagonistic mAbs to chemoattractant receptors has also proven difficult in the past. There is therefore a need for an improved method for generating high affinity antibodies against polypeptides such as G-protein coupled receptors and chemoattractant receptors.